catena-Poly[[{bis­[tetra­aqua­(2-hy­droxy-3,4-dioxocyclo­but-1-en-1-olato-κO 1)bariumstrontium(0.35/0.65)]di-μ-aqua}­bis­(μ-2-hy­droxy-4-oxocyclo­but-1-ene-1,3-diolato-κ2 O 1:O 3)] monohydrate]

Chahrazed Trifa; Amira Bouhali; Sofiane Bouacida; Chaouki Boudaren; Thierry Bataille

doi:10.1107/S1600536811002996

. 2011 Jan 29;67(Pt 2):m275–m276. doi: 10.1107/S1600536811002996

catena-Poly[[{bis[tetraaqua(2-hydroxy-3,4-dioxocyclobut-1-en-1-olato-κO ¹)bariumstrontium(0.35/0.65)]di-μ-aqua}bis(μ-2-hydroxy-4-oxocyclobut-1-ene-1,3-diolato-κ² O ¹:O ³)] monohydrate]

Chahrazed Trifa ^a, Amira Bouhali ^a, Sofiane Bouacida ^a,^b,^*, Chaouki Boudaren ^a, Thierry Bataille ^c

PMCID: PMC3051722 PMID: 21522923

Abstract

The title structure, {[Ba_0.71Sr_1.29(C₄HO₄)₄(H₂O)₁₀]·H₂O}_n, is built from dimers of edge-sharing monocapped square antiprisms [(Ba/Sr)O₃(H₂O)₆], in which barium and strontium are statistically disordered [ratio 0.353 (8):0.647 (8)] on the same crystallographic site. Such dimers are connected via bidentate hydrogen squarate groups [HC₄O₄]⁻, leading to chains that propagate along the b axis. Inter- and intramolecular O—H⋯O hydrogen bonds maintain the crystal packing through a three-dimensional network.

Related literature

For related transition metal squarate structures, see: West & Niu (1963 ▶); Lee et al. (1996 ▶); Haben-Schuss & Gerstein (1974 ▶). For related alkaline earth squarate structures, see: Robl & Weis (1986 ▶, 1987 ▶); Robl et al. (1987 ▶); Bouayad et al. (1995 ▶). For related rare earth squarate structures, see: Trombe et al. (1988 ▶, 1990 ▶, 1991 ▶); Bénard-Rocherullé & Akkari (2005 ▶). For the first synthesis of squaric acid (3,4-dihydroxycyclobut-3-ene-1,2-dione), see: Cohen et al. (1959 ▶).

Experimental

Crystal data

[Ba_0.71Sr_1.29(C₄HO₄)₄(H₂O)₁₀]·H₂O
M _r = 860.70
Monoclinic,
a = 25.3592 (9) Å
b = 8.8993 (3) Å
c = 14.1286 (5) Å
β = 119.974 (2)°
V = 2762.07 (18) Å³
Z = 4
Mo Kα radiation
μ = 3.62 mm⁻¹
T = 295 K
0.09 × 0.08 × 0.08 mm

Data collection

Nonius KappaCCD diffractometer
18241 measured reflections
3173 independent reflections
2616 reflections with I > 2σ(I)
R _int = 0.077

Refinement

R[F ² > 2σ(F ²)] = 0.033
wR(F ²) = 0.088
S = 1.06
3173 reflections
239 parameters
4 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.96 e Å⁻³
Δρ_min = −1.02 e Å⁻³

Data collection: COLLECT (Nonius, 1998 ▶); cell refinement: SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO (Otwinowski & Minor, 1997 ▶) and SCALEPACK; program(s) used to solve structure: SIR2002 (Burla et al., 2003 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Berndt, 2001 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811002996/bq2274sup1.cif

e-67-0m275-sup1.cif^{(29.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811002996/bq2274Isup2.hkl

e-67-0m275-Isup2.hkl^{(152.6KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Ba1—O1	2.728 (2)
Ba1—O5	2.688 (2)
Ba1—O9W	2.729 (3)
Ba1—O10W	2.772 (3)
Ba1—O11W	2.722 (3)
Ba1—O12W	2.644 (3)
Ba1—O13W	2.782 (3)
Ba1—O3ⁱ	2.6720 (19)
Ba1—O10Wⁱⁱ	2.786 (2)

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Symmetry codes: (i) Inline graphic ; (ii) .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1W⋯O2ⁱⁱ	0.82 (4)	2.55 (4)	2.874 (2)	105 (3)
O1W—H1W⋯O7ⁱⁱⁱ	0.82 (4)	2.47 (4)	3.193 (3)	148 (4)
O4—H4⋯O5^iv	0.82	1.79	2.603 (3)	171
O8—H8⋯O1	0.82	1.77	2.575 (3)	169
O9W—H9A⋯O1W^iv	0.84 (3)	2.47 (3)	3.197 (5)	147 (4)
O9W—H9B⋯O3^v	0.87 (4)	1.97 (4)	2.821 (3)	167 (5)
O10W—H10A⋯O11W^vi	0.78 (5)	2.54 (4)	3.150 (4)	137 (4)
O10W—H10B⋯O2ⁱⁱ	0.86 (4)	1.88 (4)	2.711 (4)	164 (4)
O11W—H11A⋯O1W	0.86 (3)	2.06 (4)	2.880 (5)	159 (4)
O11W—H11B⋯O6^vii	0.87 (4)	1.91 (4)	2.777 (3)	176 (5)
O12W—H12A⋯O13W^viii	0.83 (4)	2.00 (4)	2.803 (3)	164 (4)
O12W—H12B⋯O7^ix	0.84 (4)	1.87 (4)	2.711 (3)	178 (5)
O13W—H13A⋯O6^x	0.86 (5)	2.00 (4)	2.736 (3)	143 (3)
O13W—H13B⋯O8^xi	0.84 (4)	2.24 (4)	3.014 (3)	154 (4)

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Symmetry codes: (ii) Inline graphic ; (iii) ; (iv) ; (v) ; (vi) ; (vii) ; (viii) ; (ix) ; (x) ; (xi) .

Acknowledgments

The authors thank the Unité de Recherche de Chimie de l’Environnement et Moléculaire Structurale, CHEMS, Université Mentouri–Constantine, for financial support. SB thanks Dr Thierry Roisnel, Centre de Diffractométrie X (CDIFX) de Rennes, Université de Rennes 1, France, for his technical assistance in the data collection.

supplementary crystallographic information

Comment

Squaric acid, (3,4-dihydroxycyclobut-3-ene-1,2-dione, H₂C₄O₄, H₂sq), synthesized for the first time by Cohen et al. (1959), has been of interest because of its cyclic structure and its possible aromaticity. (West et al., 1963) have described the preparation from aqueous solutions of 'isostructural' divalent metal squarates of general formula MC₄O₄.2H₂O, and predicted a chelated linear polymer structure, the structure of Ni(C₄O₄).2H₂O being reported later by (Haben-schuss et al., 1974). In the structurally well understood metal squarates M(C₄O₄)(H₂O)₄ (M = Mn, Fe,Co, Ni, Zn) (Lee et al., 1996), the C₄O₄^2- entity serves as a bridging ligand between two metal ions (µ-2) in trans positions while it acts as a fourfold monodentate (µ-4) ligand between metals in the three-dimensional polymeric structures of M(C₄O₄)(H₂O)₂ (M = Mn, Fe, Co, Ni, Cu, Zn). However, the cyclic group only chelate the largest cations such as alkaline earth (Robl & Weis, 1986, 1987; Robl et al., 1987; Bouayad et al., 1995) or rare earth elements (Trombe et al., 1988; Trombe et al., 1990; Trombe et al., 1991; Bérnard-Rocherullé & Akkari, 2005).

Surprisingly, the crystal structures of barium squarate hydrate and strontium squarate hydrate are rather different. It is of interest to explore the possibilities of mixing cations, to obtain new compounds or solid solutions. Here, we synthesized hemi hydrate barium strontium squarate, [Ba0.35 Sr0.65 (HC₄O₄)₂ (H₂O)₅] 0.5 H₂O, for which the Ba / Sr ratio has been determined from EDX and single-crystal diffraction data.

The asymmetric unit contains two metal atoms, two hydrogen squarate anions, five aqua ligands and half water molecule. The Barium and Strontium ions are disordered on the same site as well as a solvent water molecule situated on the twofold axis at (4 e; 0, y, 1/4).

The structure is formed from chains, bridged by the hydrogeno squarate group acting as a bidentate ligand in a trans position (Fig. 2). The three-dimensionality is ensured by a strong O—H···O hydrogen bond (Table 1. The free water molecule is sandwiched between these chains.

Experimental

All chemical were commercially available and used as received. For convenience, 3,4-dihydroxycyclobut-3-ene-1,2-dione (H₂C₄O₄) is named squaric acid hereafter. Typically, Poly [pentaaqua di squarato barium strontium] hemi hydrate was synthesized by hydrothermal reaction starting from a mixture of barium chloride BaCl₂, 2H₂O (2 mmol), strontium chloride SrCl₂, 6H2O (2 mmol) squaric acid H₂C₄O₄, oxalic acid H₂C₂O₄, 2H2O (1 mmol) and water (4 ml). The whole was stirred for 30 minutes until homogeneous. The final mixture was sealed in a 23 ml Teflon-lined acid digestion bomb (Parr) and heated at 423 K for 48 h under autogeneous pressure and then cooled down to room temperature. The yellow crystalline product obtained were collected by filtration, thoroughly washed with distilled water and ethanol, and finally dried at room temperature. The chemical formula was derived from the Ba/Sr ratio (1/2) obtained by energy dispersive X-ray spectrometry (EDX), and from the crystal structure determination reported below.